cuda-mp

CUDA Multi-Precision Library (Used for prime finding)

How does it work?

This Multi-precision library works by defining all numbers as BCD types. Each digit is stored as a (char) index in an array, with the values from 0-9 (BCD).

Advantages

1. Makes it much easier to program/understand

Disadvantages

1. Since each digit is stored in Base10 instead of Base2^32 (for a uint32_t), there are a lot of wasted bits. e.g.: 2048-bit arithmetic requires at least 1234 bytes, one for each digit. While 2048-bit arithmetic using bit storage (non-bcd) only requires 64 bytes. While the number storage only requires half that (617 digits, and 32 bytes respectively), double width is needed for multiplication operations.

CUDA Speedup

In order for this code to provide a speedup over standard CPU-based bigint libraries, it must be run in parallel across many CUDA threads. Each operation runs serially on a single thread which means that multiple operations should be performed at once with different numbers across multiple threads.

FAQ

• Why are the early commits so bunched up and funky?

  • I started working on this project without VCS, and used my Seafile server to sync the code across devices. The early commits are essentially just snapshots of the code directory over the last week, just condensed into a few commits for sake of versioning with VCS.